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Proportion Problems

This has been racking my brain for awhile, and I know I have it right, but something is missing.

1. A person earns 850 euros in one week. How much will she earn in 3.5 weeks?

This seemed simple enough, so I just multiplied 850 by 3.5 and got $2,975. I know there's one more step, and I can't find it.

2. A picture is 73/4 inches wide and 81/2 inches high. If you wish to enlarge the width to 10 inches, how high will the picture be? Express in fractions instead of decimals.

I converted the fractions into decimals so I can get the fraction answer. I came up with 7.75/8.5 = x/10 = I then got 77.5 over 8.5 and came up with 911/100. Obviously this is wrong, but I can't figure out the step I missed here.

3. There's 5/4 of a triangle and 2/x of another one, I'm supposed to find the missing piece.I come up with 8/5. I'm stuck on where to go from here.

Any help would be appericated.
 

Doc Al

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simplywrite said:
1. A person earns 850 euros in one week. How much will she earn in 3.5 weeks?

This seemed simple enough, so I just multiplied 850 by 3.5 and got $2,975. I know there's one more step, and I can't find it.
This one's just fine---no missing steps.

2. A picture is 73/4 inches wide and 81/2 inches high. If you wish to enlarge the width to 10 inches, how high will the picture be? Express in fractions instead of decimals.

I converted the fractions into decimals so I can get the fraction answer. I came up with 7.75/8.5 = x/10 = I then got 77.5 over 8.5 and came up with 911/100. Obviously this is wrong, but I can't figure out the step I missed here.
You messed up the statement of ratios. It looks like you tried to use:
[tex]\frac{W_1}{H_1} = \frac{W_2}{H_2}[/tex]
But you put [itex]H_2 = 10[/itex] instead of [itex]W_2 = 10[/itex].
3. There's 5/4 of a triangle and 2/x of another one, I'm supposed to find the missing piece.I come up with 8/5. I'm stuck on where to go from here.
I don't understand this problem.
 

NateTG

Science Advisor
Homework Helper
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simplywrite said:
This has been racking my brain for awhile, and I know I have it right, but something is missing.

1. A person earns 850 euros in one week. How much will she earn in 3.5 weeks?

This seemed simple enough, so I just multiplied 850 by 3.5 and got $2,975. I know there's one more step, and I can't find it.
Right. You forgot to account for taxes ;). Just kidding, that looks correct to me.

2. A picture is 73/4 inches wide and 81/2 inches high. If you wish to enlarge the width to 10 inches, how high will the picture be? Express in fractions instead of decimals.

I converted the fractions into decimals so I can get the fraction answer. I came up with 7.75/8.5 = x/10 = I then got 77.5 over 8.5 and came up with 911/100. Obviously this is wrong, but I can't figure out the step I missed here.
I'd suggest staying with fractions if you're comforatable:

So you've got an inital aspect ratio:
[tex]\frac{width}{height}=\frac{\frac{73}{4}}{\frac{81}{2}}=\frac{146}{324}=\frac{73}{162}[/tex]
and then you want so solve for the same aspect ratio with a different width:
[tex]\frac{10}{h}=\frac{73}{162}[/tex]
[tex]10\times162=73 h[/tex]
[tex]\frac{1620}{73}=h[/tex]

Of course, since [tex]\frac{73}{4} > 10[/tex] and the problem mentions increase to 10 inches, I'm guessing you copied it incorrectly.

3. There's 5/4 of a triangle and 2/x of another one, I'm supposed to find the missing piece.I come up with 8/5. I'm stuck on where to go from here.

Any help would be appericated.
I can't quite follow what you're doing, but I'd guess that you'should be getting [tex]\frac{8}{5x}[/tex] instead of [tex]\frac{8}{5}[/tex].
 
The exact problem is

I have two triangles, one is 5 inches on the left and 4 inches at the bottom. Another one is 2 inches on the left side and x on the bottom. The idea is to find the missing piece of that one, that's what I was trying to say.
 

NateTG

Science Advisor
Homework Helper
2,449
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simplywrite said:
The exact problem is

I have two triangles, one is 5 inches on the left and 4 inches at the bottom. Another one is 2 inches on the left side and x on the bottom. The idea is to find the missing piece of that one, that's what I was trying to say.
Can you fill in the spaces below?
5 is to 4 as _ is to _
 
5 is to 4 as 2 is to x.

One triange is 5 inches on the left, and 4 at the bottom. Another is 2 inches to the left. The idea is to find the x at the bottom of the other triange.
 
Let me redo this one:

A picture is 7 3/4 inches wide and is 8 1/2 inches high. If you enlarge the picture by 10 inches, how high will the picture be expressed as a fraction over a decimal?
 

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